Patch: apply health_check commit without the commit

config/settings/base.py

@@ -109,6 +109,8 @@
 MIDDLEWARE = [
     # Generate request Id
     "django_datadog_logger.middleware.request_id.RequestIdMiddleware",
+    # Itou health check for Clever Cloud, don’t require requests to match ALLOWED_HOSTS
+    "itou.www.middleware.public_health_check",
     # Django stack
     "django.middleware.gzip.GZipMiddleware",
     "django.middleware.security.SecurityMiddleware",

itou/www/middleware.py

@@ -1,3 +1,8 @@
+import sentry_sdk
+from django.core.cache import cache
+from django.core.files.storage import default_storage
+from django.db import connection
+from django.http.response import HttpResponse, HttpResponseServerError
 from django.utils.cache import add_never_cache_headers
 
 
@@ -9,3 +14,34 @@ def middleware(request):
         return response
 
     return middleware
+
+
+def public_health_check(get_response):
+    def middleware(request):
+        """
+        Bypass ALLOWED_HOSTS checks
+        CleverCloud probes access this path through IP directly, we don’t want to serve
+        a 400 BadRequest because the request Host header is not in the ALLOWED_HOSTS.
+        """
+        if request.path == "/check-health":
+            try:
+                with connection.cursor() as c:
+                    c.execute("SELECT 'check-database-connection'")
+                cache.get("check-cache-connection")
+                default_storage.exists("check-s3-file-access.txt")
+                body = b"Healthy\n"
+                return HttpResponse(
+                    body,
+                    content_type="text/plain",
+                    charset="utf-8",
+                    # CommonMiddleware is later in the middleware chain, and it checks ALLOWED_HOSTS.
+                    headers={
+                        "Content-Length": str(len(body)),
+                    },
+                )
+            except Exception as e:
+                sentry_sdk.capture_exception(e)
+                return HttpResponseServerError()
+        return get_response(request)
+
+    return middleware

tests/www/test_check_health.py

@@ -0,0 +1,21 @@
+class TestCheckHealth:
+    def test_get(self, client):
+        response = client.get("/check-health")
+        assert response.status_code == 200
+        assert response.charset == "utf-8"
+        assert response["Content-Type"] == "text/plain"
+        assert response["Content-Length"] == "8"
+        assert response.content.decode() == "Healthy\n"
+
+    def test_get_as_clever(self, client):
+        response = client.get(
+            "/check-health",
+            # CleverCloud probes connect directly through the IP, their HOST is not in the ALLOWED_HOSTS.
+            HTTP_HOST="10.2.2.2",
+        )
+        assert response.status_code == 200
+
+    def test_get_with_error(self, client, mocker):
+        mocker.patch("itou.www.middleware.connection.cursor", side_effect=Exception("Boom!"))
+        response = client.get("/check-health")
+        assert response.status_code == 500